Sydney is enduring its driest summer in 72 years, with much of NSW parched by three heatwaves in January and little relief in sight, meteorologists say.

The Harbour City has recorded just 48.4 millimetres of rain at its Observatory Hill site since December 1, a little over a quarter a typical amount for December and January, said Acacia Pepler, a climatologist at the Bureau of Meteorology.

In January, Sydney collected just 17.4 millimetres of rain, or less than a fifth of the long-term average, making last month the driest January since 2003. Temperatures were about 1 degree above average.

Much of eastern NSW had a very dry January. Photo: BoM

Statewide, January was the 10th hottest on record, with average maximum temperatures 2.7 degrees above the norm. Sea breezes helped to shield coastal regions – including Sydney – from the worst of the heat.

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“There were three major heatwaves for the month but none of them managed to penetrate on to the coastal strip,” Ms Pepler said.

Nationally, January's mean temperature was about 0.9 degrees above the long-term average, placing it 12 warmest on record, said Blair Trewin, a senior climatologist with the bureau.

January rainfall percentages for NSW. Photo: BoM

Unlike January 2013 - which was the hottest for any month in a century of records for Australia - last month did not see the repeat of a continent-wide "dome of heat".

Instead, sweltering conditions across south-east regions - Victoria recorded monthly averages 3 degrees above normal - were offset by much of WA or the Northern Territory recording close to or below average temperaures for the month.

NSW was joined by Victoria, Tasmania and South Australia in recording maximum anomalies within the top ten on record, while mean temperature anomalies were the eighth-highest on record for Victoria and South Australia, and ranked ninth-highest for Queensland, the bureau said.

Maximum temperature anomalies across NSW in January.

Heatwaves

Blocking high-pressure systems in the Tasman have helped stoke a series of heatwaves in south-eastern Australia that are continuing.

Adelaide, for instance, had its hottest February day on record when the mercury climbed to 44.7 degrees on Sunday.

Canberra, meanwhile, is expecting a maximum of 37 degrees on Monday. If achieved, it would be the first time the capital has clocked up six consecutive days of 37 degrees or warmer in records going back to 1939. The current sequence of five such days has been recorded only twice before, including a spell last month.

Agriculture Minister Barnaby Joyce is reportedly seeking $7 billion for a bailout package to aid drought-hit farmers. Most of Queensland is already declared to be in drought, with the band of dry regions now stretching well into NSW.

The heat hasn't helped. Walgett in the state's north-west reported 49.1 degrees on January 3, the warmest day anywhere in NSW since 1939, the bureau said.

Inland regions will be hot again on Monday, with Deniliquin in the Riverina expecting 43 degrees and Wagga Wagga 40.

Little sign of rain relief

Sam Brown, a meteorologist with Weatherzone, said a few showers were possible on Tuesday for parts of the coast from Batemans to Newcastle.

A strip from Port Macquarie to the Queensland border can expect similar conditions on Wednesday, with showers likely to be light, isolated and less than 10 millimetres.

“Western parts of the state won't get much at all,” Mr Brown said.

A modest cool change will bring some relief from the heat but also “quite gusty” winds on Tuesday or Wednesday, elevating the fire risks, he said.

For Sydney, conditions will turn cooler with a maximum of 27 on Monday dropping to 24 on Tuesday and 22 on Wednesday.

Weather models indicate there is the potential for a few showers for Sydney and eastern parts of the state towards the end of next week “but nothing super heavy just yet”, Mr Brown said.